The invention relates to the art of making reclosable bags, the material for making such bags, and method and means for making the same and is particularly concerned with bags formed of flexible plastic film with an extruded resiliently flexible plastic profiled reclosable separable fastener at the bag top.
The art of making reclosable bags equipped with extruded plastic profiled reclosable fasteners has seen a long period of development as reflected in numerous patent disclosures. It has been conventional practice to extrude plastic film in tubular form with the profiled separable fastener means coextruded along with and parallel to the longitudinal formation axis of the tubular film, that is, the direction in which the tube is extruded. On the other hand, prefabricated separable fastener profile strips have been secured to film. Generally, the film is in a continuous sheet and to form a bag, the film is doubled onto itself with the folded edge forming the bottom of a series of bags. In this arrangement, the fastener profiles extend in the longitudinal axis direction of the continuous film sheet.
By way of example, U.S. Pat. No. Re. 29,043 is referred to as disclosing coextrusion of web and fastener means and forming the same into bag sections.
U.S. Pat. No. 3,948,705 exemplifies the technique of securing reclosable separable fastener strips to plastic film parallel to the longitudinal formation axis of the web by fusion or heat seal methods.
Attachment of separable fastener strips parallel to the longitudinal formation axis of the web by adhesive means is exemplified in U.S. Pat. No. 4,372,793; 4,354,541; and 4,355,494.
U.S. Pat. No. 4,046,408 discloses separably interlockable fasteners along the edges of the plastic sheet material having generally arrow shaped profiles, the fasteners being either integrally extruded with flat sheets or tubes of plastic film, or supplied in the form of extruded strips attached to the web or film by heat sealing.
It has been recognized, however, in the disclosure of U.S. Pat. No. 4,655,862 that advantages accrue in a method and apparatus for making bag material by forming the material by securing to the film of the material an extruded plastic profile reclosable fastener strip lengthwise across the material and at right angles to the formation axis of the film.
According to the above prior art disclosures, with the exception of U.S. Pat. No. 4,655,862, it is necessary to provide a pair of longitudinally extending complementary profile fastener strips along the longitudinal extent of the bag material. When the material is folded upon itself, the fastener profiles will be brought together in face-to-face relationship and aligned with one another. The strips are aligned in interlockable relation with the ribs facing the grooves. The fastener strips extend along the top or bag mouth edges of the bag sections. When the bag material is folded laterally to bring the fastener strips together, the folded bag material is sealed cross-wise at spaced intervals to form separate bags.
In another method of forming bags, separate strips of the web of film material each carrying the complementary profile fastener strips are laid on top of each other to provide bag sidewalls. The side and bottom edges of the bag walls must be seamed together to complete the bags.
Those prior techniques do not necessarily limit the length of bags to be produced thereby, that is, the length from the bag top end to the bottom end of the bag, unless the bags are supplied for filling by the type of filling machines commonly referred to as form, fill and seal machines, such as exemplified in U.S. Pat. No. 4,355,494.
Where the fastener strip means are located longitudinally along the length of the bag making web material, the length of the bags that can be produced in the form, fill and seal machines is limited to the diameter of the filling nozzle about which the film or web material is progressively wrapped. Further, unless the fastener profiles are interlocked before the bag forming material is wrapped about the forming extent of the filling nozzle or at least before the usual longitudinal sealing of the joined longitudinal edges or margins of the bag forming material, there is a considerable problem with attaining interlockable registration of the fastener profiles.
Furthermore, if and when used on vertical form, fill, and seal apparatus, bag material as shown in U.S. Pat. No. 4,355,494 has certain shortcomings, as the material will produce finished bags having reclosable fastener means running in the longitudinal formation direction of the material and, thus, in a vertical direction along the bags. Such bags may not be commercially acceptable for some products, e,g., some types of candies, potato chips, and other snack foods.